Oh, I was just wanting to clarify the "Apple co-founded".
They had the Newton project, found ARM did a better job than the other options, but there were a few missing pieces. They funded the spun out project so they could throw ARM a few new requirements for the CPU design.
As a "cofounder" of ARM, they didn't contribute technical experience and the architecture did already exist.
I believe they had a big hand in ARM64. Though best reference I can find right now is this very site: https://news.ycombinator.com/item?id=31368489